1. Field
The present application relates generally to wireless communications, and more specifically to methods and systems to enable associated user equipment to acquire an access point base station, within a building.
2. Background
Typical radio access cellular networks operate by way of various radio transmission devices, or base stations. These base stations provide wireless access to wireless mobile devices, such as cellular phones, to a core network of a cellular service provider. The base stations along with various data routing and control mechanisms (e.g., base station controllers, core and edge routers, and so on) facilitate remote communication for the mobile devices. As communication service providers expand base station coverage, more land areas can be covered by the radio access network. However, some areas can be difficult to provide reliable radio coverage, for various reasons such as population, high mobile traffic, interference with other transmitters, or materials that absorb base station transmission (e.g., dense, concrete and steel buildings, underground facilities, and the like).
Indoor cellular reception in particular has issues such as high interference, especially in higher floors subject to significant pilot signal noise pollution. Some venues have high capacity for people within a small area (e.g., shopping mall, airport terminal). These high density communication venues thus strain available capacity. It can be difficult to provide seamless integration of indoor cells with outdoor cells, not only managing interference but also in association, neighbor lists and handover procedures.
One solution to provide mobile communication support to areas where radio access is difficult, is a ‘personal’ base station, or femto Base Station (BS) (also termed, e.g., a home Node B or Femto cell). A BS can be a relatively small range device (compared with standard radio network base stations, such as a Node-B) that facilitates wireless communication over a licensed cellular radio band (as opposed to an un-licensed band, utilized by wireless local area network routers). In an exemplary aspect, the BS can be of any size and attaches to a large BTS to serve a large coverage area and amount of user equipment within the coverage area. The BS can maintain a wireless link with cellular devices over such a network band, in a similar manner as a Node-B base station. Consequently, a BS can provide small range cellular coverage for an area that does not receive a good signal from a radio access base station. Often, an individual consumer might utilize a BS in their home, an apartment building, an office building, and so on, for personal cellular access. In addition to mobile phone networks currently in place, a new class of small base stations has emerged, which may be installed in a user's home and provide indoor wireless coverage to mobile units using existing broadband Internet connections. Such personal miniature base stations are generally known as access point base stations, or, alternatively, Home Node B (HNB) or femto cells. Typically, such miniature base stations are connected to the Internet and the mobile operator's network via DSL router or cable modem.
In an attempt to create a more economical solution, typical solutions to achieve uniform radio coverage are to install some sort of distributed antenna system in the building. These can be passive or active (i.e., with electronic gain). These systems are available commercially and consist of cable, fiber, amplifiers, optical equipment and antennas for local in-building coverage. The downside of these systems is that they tend to be quite expensive, labor intensive and difficult to plan and integrate into the external macro cell system. However, in order to provide uniform coverage throughout a facility, the costs can be prohibitive in placing a large number of such RF devices. The RF equipment is cost driven by the fact that the entire radio channel is transported in the cable network. If the system is analog, then expensive analog radio equipment is necessary to implement the system, and the concerns for proper gain and amplitude become expensive design drivers. If the system is digital, then maintenance of proper gain and amplitude can be easier to implement but because the entire radio channel (actually it is typically multiple radio channels) then the digital data rates in the system can become quite large, in the several hundreds of megabit range. This high data rate precludes the use of low cost components are cables.